> For the complete documentation index, see [llms.txt](https://chembl.gitbook.io/unichem/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chembl.gitbook.io/unichem/web-application/connectivity-search.md).

# Connectivity Search

Find compounds and its sources by its InChI connectivity layers, i.e., formula, connections, H atoms and charge layers of the InChI.  Similar to the compound search, compounds to compare connectivity with can be looked up using InChI, InChI Key, a source compound ID or a Unique Compound ID (UCI)

{% hint style="warning" %}
The image representation in the Searched Compound card is an approximated depiction of the found molecule. It might not represent exactly the found compound. For a better image of the compound please follow the link to one of the found sources.
{% endhint %}

### InChI and InChIKey

Find the sources linked to the [IUPAC international chemical identifier ](https://iupac.org/who-we-are/divisions/division-details/inchi/)for your compound or its hashed InChI form. 

### Source Compound ID

Compounds can be found by the ID assigned on a source database, simply select the Source of the compound and in the box right next to the selector enter the ID for that particular compound in the given Source.

### UniChEM Identifier (UCI)

The UCI (UniChEM Identifier) is the number we use to identify a distinct compound with its linked sources in our database.